A huge earthquake will herald the end of the world and the destruction of mankind today, an evangelical Christian leader is warning.
The head of a US Christian broadcaster says he is certain the apocalypse is upon us and may watch the drama unfold at home on television.
The theory is that those worth saving will go to heaven while the rest of humanity will be left to face oblivion after a day of judgement — beginning at 7am in the UK — accompanied by the second coming of Christ.
Harold Camping, 89, has made similar forecasts before however.
He previously predicted Jesus would return to Earth in 1994 - and atheists have reacted to his latest prophecy by arranging a "countdown to back-pedaling" party in anticipation he will be left red-faced.
Camping, head of the 140-station Christian radio network Family Stations, says true believers will progress to the afterlife while those left behind will perish at some point in the chaos of the next couple of months as the world is destroyed.
All non-believers are due to be dead by October 21 - and there is no doubt in his mind.
The former engineer said: "We know without any shadow of a doubt it is going to happen.
"We do not have a Plan B at all. There is no possibilty that it will not happen because all of our information comes from the Bible."
Camping's supporters have posted around 2,200 road-side posters advertising the up-coming catastrophe while dozens of his followers have driven across the US to warn the population of their impending doom.
He himself will be at home with his wife in northern California.
"I'll probably try to be very near a TV or a radio or something," said Camping.
"I'll be interested in what's happening on the other side of the world as this begins."
Sam Mulvey, 33, organised the atheists' countdown bash.
He said: "If the world still exists the next day, Family Radio is going to have to say something and most of the time they backpedal, and that's what we're counting down to."
Camping bases his predictions on his reading of the Bible and a timeline dating back to ancient events including the story of a flood survived by Noah.
But even those who broadly agree with his ideas don't like the way he addresses the prospect of Armageddon.
Apocalyptic author Jerry Jenkins said: "As a believer, I'm already a kook compared to most people, so for someone to choose a date and get everyone excited about a certain time, my problem is it makes us look worse."
